For a specific type of cell after 3 hours, the concentration of cells per ml of solution is about 400/mL. After 10 hours the concentration has gone up to 2000/mL. Determine the initial concentration of cells. Assume growth kinetics are X = X0e^ut where X0 is initial concentration of cells (i.e. number of cells at t=0), u is the rate constant and X is the concentration of cells after a certain time has elapsed.